Carburetor



atented pr. 27, 1926.

nyppnuanoamea January 10,1920. serial nu; seater'.

To all whom 'it may concern:

.Be it known that I, Wnmln ScHoor, a citizen of the United States, residingat Milwaukee, county of Milwaukee, and State of Wisconsin, have invented new and useful improvements in Carburetors, of which the following is a speciication.

rlhis invention relates to improvements in carburetors for internal combustion engines.

v @ne object of -this invention is to provide a carburetor that will maintain a substantially constant mixture for all settings of the throttle valvev and for all engine speeds with or without load.. l am aware that certain authorities have advanced the proposition that a substantially constant mixture is not desirable under all conditions. rdinarily, however, where this opinion is advanced and any reason is assigned for it, the reason given is based upon chartsof engine performanoein tests involving .determinations ofthe fuel consumption as compared with the brake horse power'output of such enginesi lt can beshown that charts of performance derived through the above method are fallacious in that at the higher ranges of speeds and at the lower ranges of speeds the work done by any engine can not accurately be ascertained by a brake horse power test. llt can be shown that an internal combustion engine running at comparatively high or at comparatively low speeds does work other than that exerted vthrough. the brake and that therefore the apparent output of work at the brake becomes comparatively lowered at such speedswith reference to theamount of -`ilzuel consumed, thus causing the charts of performance to assume the peculiar curve upon which the opinions `above referred to are most often based. For this reason and be# cause theoretically a constant mixture of fuel and air should give constant results in work output under all-conditions ofengine operation, lprefer to provide a carburetor ada ted to maintain a substantially constantmixture in so far as such a mixture is possible to obtain in practice. To provide such a carburetor is the principal object of this invention. A further lobject is to provide a carburetor with means for temprarily and substantially instantaneouslyaugmenting the supply of fuel for a sudden opening ofthe throttle valve and decreasing the'supply of fuel for a sudden closing of thethrottle valve. ,The temporarily operative means above referred tc is not intendedtojchange, norv does it erate to produce a substantially n; :i mixture but will also produce an ideal mixvchan e, the substantially constant mixture whic it is my principal object to attain; on the contrary, the function of the means above mentioned is to maintain the mixture constant under circumstances such as might tend to alter the proportion of .fuel and air.

A further object is to provide a carburetor twhich will improve the economy of operaion.

A further object is to provide a carburetor with means for aiding in starting the motor. A further object is to provide a carburetor in which the throttling, the augmenting or decreasing ofthe supply of fuel, and the aiding of the starting of the motor are all obtained by mechanism under a single lever control. v

-A 'further object of this invention is to provide a carburetor in which the mixture under normal carburetor operation will be 'entirely dependent upon air tlow through the carburetor. lt will not be adected by such factorsas changes lin engine speed or load or by changes in engine design, whereby within vits eEective capacity the carburetor of my invention may e used with various types of engines under various conditions without ad- Justment.

e Itis a further object of this invention to provide a carburetor which will not ture such as is adapte to enable an internal combustion engine to give a maximum work output in proportion to the amount of fuel supplied thereto, and whereby an excess of fuel will not be supplied at either high or l'ow engine s eeds, and .an engine using a carburetor o this design will not become overheated through'the combustion of fuel in excess. of that required for engine operation.

ln the drawing:

rlhe tigure is a vertical through the carburetor'.V v

The' carburetorl comprises a main casing which is formed primarily of three members, 1 `the u per portion, 2 the centralv ortion, and 3 t e lower portion of the carburetor. The upper portion l may be secured to the portion -2 in `any desired manner, as, for example, by boltingthe vanged portions (not shown) together. vThe casing has an air inletduct 4 which communicates with the slightly enlarged upper portion 5 of thepart sectional view only op-` l. This portion 5 communicates with a low er portion 5 which has a slightly contracted upper portion 5". This arrangement is formed to steady the mixture when the speed of the engine falls and the throttle valve is open. It has long been known that the flow o gases through orifices in thin plates follows a definite law, and that the co-eicient of discharge of such orifices, within certain limits as to size, becomes greater for high velocities of flow than or low velocities. The openings 17 are such as to operate under the aforesaid law so that their co-eiiicient of discharge is greater for high velocities o air flow than for low velocities.l I have found `by experiment that the velocity of flow through the openings 17 can be further modified by the provision exterior to said openings of the restricting wall 5", and by actual tests l have determined that at low air speeds the relative eticiency of air low into the carburetor from opening 17 is less when the restricting wall 5" is present than it is in the absence of said wall. rlhe presence of the wall does not, so far as l have been able to determine, affect the flow of air the relatively higher ranges of air speed. |The result, therefore, of the provision of the wall portion 5 is apparently to increase the variation in the co-efricient of discharge which the openings 17 have in the absence of said wall. rl`he delivery duct 6 through which the combustible mixture passes to the engine is formed in the central portion 2 and communicates with the si lostai'itially 7. rilie port in 2 has a 3 which extei ds downwardly within the portion 3. l/ithin the cylindrical portion 8 is seated the fuel delivery nozzle 9 which has shoulders 10 bearing upon cooperating shoulders formed upon the cylindrical portion 3. A fitting 11 is screwed upon the lower portion of the nozzle ,9 and extends downwardly through the bottom part of the portion 3 and is adapted to receive a nut 12 which when screwed into place, retains the casing 3 in position. The upper portion of the nozzle 9 is formed with a plurality of V-shaped projections 13 which form between them l-shaped notches 14. The entrance to the notches 14 is bevelled, as the tops of the projections 13 slope downwardly toward the center.

The throttle valve is a one piece structure and is adapted to control the iiow of es at two points between which the fuel is a apted to be supplied. it will be seen from the drawings and from the following description that the throttle valve controls both the air and the outgoing mixture. This throttle valve comprises a main cylindrical portion 15 which is provided with an integral top 16 and which is Jhir-ther provided along its cylindrical walls with a series of substantially triangular openings 17. rlhisv cylindrical member 15 slides within the cylindricylindrical opening cylindrical casing cal portion 18 of the central member and upon its downward travel serves to close the openings 17 at a varying rate as such openings pass the upper edge of the portion 18.

This is due to the inverted triangular shape' of theopenings 17, for, as is apparent from the drawings, the first portion of the openings to be closed is adjacent the apex, which is a relatively small area for a given distance of downward travel of the throttle valve. However, as the throttle valve continues on its downward travel, a greater and greater area per .unit travel of the throttle valve is closed o'. This throttle valve is slightly contracted towards its lower part and is provided at the lower end with a second cylindrical portion 19 which is adapted to slide over the projections 13 of the uel supply nozzle and to close such openings to varying extents. The operating mechanism for this throttle valve consists of a rack 20 and gear segment 22, the rack being formed upon the pin 21 which is bolted to the top 16 of the throttle valve. The gear segment 22 is fast upon a shaft 23 which shat extends outwardly through the upper side portion of the carburetor and is operated by means of a lever 24 which is adapted to be connected to one of the controls.

The casing 3 is adapted to orm the main temporary reservoir or the, gasoline, the height oiwhich in suoli casing is controlled by means of a iioat'25 which operates a valve 26 through the medium of the pivoted lever 27 rEhe valve 26 is provided with a double lower conical surface, the major part of which is ground at an angle otabout 45 and the upper portion` which seats upon the valve seat is ground at an angle of about with the axis or the valve spindle. The

valve spindle comprises a. reduced portion 27 with a lower shoulder 28 and an upper shoulder 29 rorined thereon between which works the-rounded portions 30 of the forked lever 27. The upper ortion of the valve spindle may be iute and made heavy `enough to partly balance the float 25. It 1s reduced at 31 so as to provide an extreme upper shoulder 32. This shoulder is adapted to he engaged by a portion of the shaft 33, the other half of which is cut away adjacent the shoulder 32. rThis shaft 33 extends outwardl beyond the iitting 34 and is adapted to he operated by a 'manually controlled lever 35.` The itting 34 is clamped in position by a machine screw passing through the opening 34 in a split ortion of the casing 3. The gasoline inlet 35 for the carburetor communicates with a cylindrical cavity 36 into which is screwed a fitting 37, the upper walls 38 of which are adapted to hold a gauze filter screen 39 in place. The iilter screen 39 will prevent solid material from passing to the portions of the carburetor, and such solid materials will arrasar' i Vtend to collect in the cavity 36, where they may be easily removed when the drain plug 40` `is unscrewed. The construction just described provides a means for manually opening the valve 26 so as to permit gasoline to How into the Hoet chamber independently of the operation of the float. IThis may be desirable under certain conditions, but it is not essential tothis invention. A drain plug 40 may be provided `for this cavity 36 and it will be noted that such cavity extends downwardly below. the gasoline inlet 35 so as to retain sediment therein. From the chamber formed by the casing13 the gasoline is adapted to enter a plurality of orifices 41 (one of which is shown in the section) formed in the itting -11 and to pass to the fuel supply nozzle through a small Venturi tube 42, the tapered upper portion oi which aligns with the Haring nozzle pas- As thus far described, it will be seen that when sucient suction is provided by the through the nozzle either in the form of an fine spray or stream, or else it will be partially vaporized and completely fill the diverging tube 43, or else it willv ll the diverging tube 43 in its li uid form. The particular physical state' t at the gasoline will assume within the tube 43 obviously depends upon the suction exerted upon the upper end of such tube' and the rate of flow of the gasoline throu h the ylower portion thereof. ln anyof t e three methods that it may traverse such delivery nozzle, it

is finally passed upwardly into the space between the orifices 17 'and 14 and mingles with the air passing downwardly throu h the carburetor and .is drawn throught e delivery duct 6 together with the air' with.

which it has beenl intimately mixed. it will be noted that at high engine speeds the jet velocity is higher because the passage 43 may become partially or wholly emptied and the full hydrostatic head of the fuel, due to the submerged positioning `of the nozzle, becomes edective at the entrance to the nozzle. i At slower engine speeds the jet velocity is lower, as the passageway 43 may become completely filled with fuel and the hydrostatic head becomes less effective. lt

will be further noted that the bottom por- Y tion of the throttle valve may end a slight distance above the upper points ot the triangular projections 13. By proportionin andshaping the openings 17. and 14 an nozzle and contracted upper portion 5" in the manner shown and described, it has been found that for varying engine speeds, varying loads, and for varying settings of the.

throttle, the 'mixture remains substantially constant. V 'lhat is to. say, an increase or decrease in the speed of the engine does not."

alter the proportion of the gasoline to the air nor does a change in the setting ot the throttle alter such proportion.'

In the carburetor of the present inventio, a substantially constant mixture is maintained by providing openings controlling the .diderent passages, of such a type that they have diderent characteristics. rlhus, when the velocity of air rises, an inordinate increase'in the eul does not'result for the reason that the coecient of dischar e for' the orifices 17 rises as the velocity rlses. When the velocity of the air falls the coefficient of discharge decreases, the orifices 17 odering an increased resistance to the passage of the air, thereby maintaining a sucient partial vacuum. The orifices 14 and fuel nozzle are so sloped'and proportioned that the quantity of fuel supplied will vary substantially in accordance.

' increasing rate, while the area uncovered for the openings 17 increases. at a decreasing rate. el of the valve towards open position, the increment of area increased for the openings 14 is larger than the preceding increment of increase of area, and conversely each successive increment of increase in area `for the openings .17 is less than that iinmediately preceding. l

When the throttle valve of a carburetor is suddenly opened, it is sometimes found that the suction which has been drawing the fuel into the carburetor is temporarily insucient until the engine has picked up suiiciently in speed to guard against such temporary insuiiency. l believe the temporary deficiency above referred yto to bev caused by the following conditions:

nl the eyepiece, the new of nel through I passage 43 is introduced primarily b a ditference in pressure within the car luretor and exterior thereto. The pressure exterior lof the engine and to the extent to which the suction ot the engine is relieved by the ad- .lOG

mission of air'through port 17 lfor a given v setting of the throttle valve and tor a given engine speedv the pressure within the carburetor will obviously remain constant. lt the Athrottle valve setting remains unchanged, pressures in the carburetor can be altered only by a change in engine speed -such as mi ht beoccasloned by a change in the loa upon the engine. Similarly, when the 'throttle Avalve is first opened, the

' relieve the low pressure existingV within the carburetor. Until the engine is caused to accelerate, there will be no increased demand on the. part of the engine, and consequently the more ready admission of air throu h the port 17 of the valve will tend lto ecrease the suction existing therein. In a carburetor of this design there would not, without an auxiliary fuel feed, such for example as that hereinafter to be described, be any tendency for the engine to accelerate, since the first effect produced by the openinfr of the throttle valve is, as above state to relieve the vacuum within the carburetor, and thereby actually to decrease the suction upon the fuel nozzle. Engine acceleratlon requires asupply of fuel additional to that which is required to drive the engine at the speed from which it is to accelerate. In ordinary carburetors the mixture is ordmarily maintained at all times richer than the theoretically perfect mixture, and the surplus amountof fuel is available for use in the production of engine acceleration. It 1s m aim to use an approximately perfect mixture at all times, and,therefore, at the moment the throttle valve is opened, there is no fuel being admitted to the carburetor beyond the amount which is absolutely necessary for the work of the engine under conditions existing at that time.

Therefore, when the throttle and air inlet valve is first opened and the suction within the mixing chamber is relieved by the increased eiclency of air iow through the enlarged openin corresponding stimu ation of flow through the fuel passage 43 until the flow of fuel through said assage is stimulated by some such fuel acce erator as that which is about to be described. Obviously, as soon as the additional quantity of fuel reaches the mixing chamber adjacent ports 14, it will be ta ien up by the air admitted through port 17 and vill at once reach the engine, thereby causing that acceleration which alone is capable of restoring pressure conditions within the carburetor to their proper relation to the degree to which ports 17 are open. It will particularly be noted that the means hereinafter to be described does not destroy the constant proportions of the mixture,.but, on the contrary, maintains the mixture proportions .by su plying fuel at such times as the fuel supp y would otherwise become diminished in proportion to the airadmitted.

On the 'other hand, when the throttle valve is closed the auxiliary means hereinafter to be described will operate to diminish fuel flow throu h the nozzle, thereby tending to preserve ie mixture constant. It will be seen that the initial closing movement of the throttle valve will at once com- 17, there will be non mence to cut off the supply of air admitted -through ports 17, or, rather, to increase 4decreasing the efficiency of said ports for air delivery. The engine, however, will not at once lose its speed and will therefore, for a time, continueto exert a suction demand out of proportion to the new osition of the throttle valve. This suction emand would, but for the auxiliary means above referred to, produce an excessive flow of fuel through the delivery passage 43. The auxiliary means, by withdrawing a portion of the 'fuel on its way to said passage and by reducing, in etiect, the hydrostatic head which forces the fuel into said passage, will prevent the tendency for acceleration of ful How which would otherwise exist.

Auxiliary means have been provided by this invention, which are actuated by the throttle valve and respond instantly to the movement of the throttle valve and serve to temporarily enhance the delivery of fuel when such throttle valveis suddenlyo cned. These means comprise an upper cy inder 44 within which fits a piston 45, provided with piston rings 45', which piston is connected with or is formed integrally with the stem 21 which operates the .throttle valve. An inner `cylindrical casing 46 extends downwardly on the inside of the hollow piston and serves as an additional means for securing an airtight joint for the piston and also for improving its operation. It will be noted that the air delivery pipe 47 extends downwardly at 48 to the bottom part of the cylinder. This is for the purpose of causing any gasoline that mi ht lodge within the hollow piston to be ischarged through such ipe when the piston is raised and the air above the piston compressed. It is not known exactly what causes the hollow piston to fill with fuel. Actual tests, however, have shown that it does so fill. It is presumed either that the fuel graduall v absorbs the air in a, system of passages o which the piston is a part, or else that at each operation of the throttle valve which produces air pressure in such system, a portion of the air may leak out through the packing rings of the piston so that upon the next closing movement of the throttle valve the fuel in said system will be drawn nearer to the piston in compensation for the amount of air which has thus escaped. The compressed air (or fuel) passes through the ipe 47, through the pipe 49,

through the uct 50, to an annular cavity 51 formed between the cylindrical member 8 and the fuelnozzle 9. This cavity 51 serves as an additional temporary reservoir for gasoline which is admitted thereto through an opening in the fitting 11 which opening communicates with the lower portion of the cavity 51 and is closed by a duted check valve 52. A convenient means of retaimn the check valve is provided by inserting a pm 53 in the upper tiange 54 of thev fitting 11P check valve 52 is not absolutely essential to' the operation of the device as 1t 1s obvious that some gasoline will pass into the chamber 5l through thel passages 55. v A convenient means of retaining the cylinder` in place is to provide a saw cut or spht 1n the portion l which saw cut extends into the space occupied by the cylinder 44. The opposed facesat this slit may be drawn to- .wards each other by a cap screw passing through theopening 58.

The action of this auxiliary device is as follows: Assuming that gasoline is in the reservoir formed by the casing` 3 and also that gasoline is in the cavity 51, it lwill be seen that a sudden upward movement of the throttle valve serves to compress the air 1n the upper cylinder, which air pressure acts upon the surface of the gasoline in the cavityr51 forcing it through the ducts 55, cavity 56, up through the nozzle 57. This ne, high speed streamof gasolineentrams additional gasoline ,in thefuel delivery nozzle and causes an augmented iow to occur, thereby odsetting any diminution in the dow of the gasoline which might be incident to a sudden opening of the throttle valve. Several seconds elapse before the augmented flow ceases, whereby time is iven for all of the cylinders to receive t is additional charge, thereby maintaining the substantial constancy of the mixture until the level of fuel in the nozzle 43 reaches its new'position and said nozzle commences its no'rmal function at the new engine speed.

rlhe economy of operation is improved for thereason that the augumented ow does vnot occur under normal or steady running conditions, but only when there is a sudden need for it. lin other words, the fuel nozzle is designed for the best economy and is not altered in size, but is caused to temporarily allow an increased flow by auxiliary means. When the throttle valve is suddenly closed the How through the fuel nozzle is l decreased bv the auxiliary device, as the How through the auxiliary nozzle 57 is re- -versed.

This auxiliary device is also of service in .starting for the reason that when the engine is being slowly rotated, the velocity of the gases through the carburetor may not ischarge the gasoline be such as to entrain or volatilize a suitable,

vmented iow of gasoline, partially or entirely filling V grooves 14. With the throttle' valve in partially closed position, the gasoline is then above the .lower end of the throttle valve cylinder 19 whereby the in coming air is caused to pass through the gasoline when the engine is rotated.

It may lbe that the operation of my improved carburetor will most easily be understood if ll explain in detail the Iconsiderations, both practical and theoretical, which led tothedesign and particular arrangement and proportion of parts disclosed here- 1n.

The. initial .calculations and tests upon this carburetor were made with a wide open throttle, and having worked out a carburetor having theoretically perfect performance under various conditions of speedlwith wide open throttle, the carburetor, was modified to retain its principle of operation while fitting it for slmilarly eicientoperation under varying throttle settings. .It is not to be understood that the various features were worked out exactly in the order in which they are hereinafter described, since 1n practice it was necessary to test and retest each feature Vwith others until the underlying principles were determined to be sound, andthe whole was functioning properly.

First of all, the passage 6 was designed to fit the inlet manifold of the internal combustion engine with which the tests were made. rlhe metering nozzle 42 was then' f chosen and was so designed and proportioned as to be capable of supplying at wide open throttle the amount of' fuel required to carburet the air which would be admitted through ports 17 Y-atY maximum air speeds. The position of the Venturi plug 42 was later found to have a modifying induence upon the discharge of said plug which required a change inthe size of plug which was at first thou ht necessary. rlhe particular position of p ug 42 which was .ultimately adopted resulted from the choice of a particular included angle between diametrically opposite portions of the wall of passage 43, and resulted also from a preferred ratio of the cross sectional area of said passage at its upper end to the cross sectional area of the Venturi opening in the plug 42 at its smallest point.

It has been determined by scientific experimenters that the most efficient Venturi passages have vat their discharge ends an included angle of approximately 5 degrees.

Therefore, before start-` Venturi plug 42 was so constructed. ln order that the fuel delivered through the Venturi o ening in plug 42 might continue fuel into small particles is facilitated by causing the fuel to traverse a passage ofthe type shown at 43 in which the cross sectional area progressively becomes greater at a con stant rate. it is my belief that the fuel can be most perfectly atomized (or broken up as aforesaid) if it is'led through a passage of the type shown at 43 to a point in said passage where the cross sectional area thereof bears the peculiar ratio with respect to the cross sectional area of the smallest part oi' said passage that ya gas bears to the liquid from- Which it can be formed. Consequently, T. so designed passage 43 that a'body of f uel disposed in the smallest part of the opening 'through the Venturi plug 42, and occupying a unitary axial distance in said plug would, if carried to the discharge end of passage 43 with the several constituent particlesv of said fuel in their same relative positions, just lill the upper end of said passage. There is obviously a tendency for fuel moving through a passagel of said type to progressively expand and ll the space between Athevvvalls which confine it. liquid can not so eX- pand. Consequently, if a body of fuel disposed in the throat of the Venturi opening of plug 42 should follow the tendency aforesaid it would change its traverse of passage 43 from a liquid substantially to a gas, or to relatively Widely separated particlesf My experiments indicate that theufuel does not follow the tendency aforesaid under all conditions and that in fact it does not become a gas under any conditions under which l have been able to observe it. At high fuelspeeds, however, l have determined that the fuel is very thoroughly atomized during its traverse of passage 43, and l ascribe this thorough atomization to the particular construction of the passage, in view of the considerations above noted.

The cross sectional area of the upper end of passage 43 having been thus proportioned to the cross sectional area of the smallest part of the Venturi opening through plug 42, and the relative locations of said plug and the upper end of said passage having been determined by the theoretical considerations aforesaid, it Was necessary next to provide a throttle device capable when open of permitting the passage of the maximum desired quantity of mixture. l also considered it desirable so to shape the throttle valve openings 14 that such openings might increase in area proportionately to the square of the distance through which the throttle valve was to be moved in opening. Furthermore, in order to have as few variable factors as possible allee-ting the operation of my carburetor, l desired to provide ports which `would have comparatively constant co-eliicient of discharge, relatively unatiected by changes in velocity of the mixture passing therethrough. lt was my theory also that by a peculiar design of throttling device, l might facilitate the mixture of air and fuel.

The ports 14 were designed with all of the above considerations in view. rlheir shape and their relation to the tubular portion 19 of the throttle valve is such that as the throttlc valve is moved upwardly to open said ports, the area of the ports will increase as the square of the distance through which the throttle valve is moved. rlhecapacity of the ports is such, if the dimensions shown in the drawing forming a part of this application are followed, that such ports are capable of supplying the full desired quantity of combustible mixture. The peculiar form of the pyramidal projections 13 between said ports is determined With reference to the coeiicient of etllux of the ports, and it was my object in designing the elements 13 so to form them that the co-eliicient of efilux of said ports would remain substantially constant, thereby relieving the carburetor of one ossible variable factor which might affeet its performance. The elements 13 were also designed as shown to conform to my the ory that their peculiar shape facilitates the mixing of air and fuel adjacent the outlet to the .passage 43.

Except as otherwise explained herein, the operation of the Venturi metering plug 42 and the operation of the mixture ports 14 are believed to be both substantially con. stant in the sense that the co-eiicient of eiluX of a properly designed Venturi passage is substantiallyconstant, and, so far as l have been able to ascertain, the co-efiicient of efflux of the openings 14 is also substantially constant. l regard it as an advantage to have few variable factors affecting the operation of a carburetor. The air admission ports 17, which are simultaneously variable in size as aforesaid, are adapted primarily to control the operation of the entire carburetor at any given throttle setting. Their combined area, as shown, is such that with due consideration for their co-elicient of discharge, they are capable of permitting the free passage of the maximum desired quantity of air to be carbureted and drawn through the throttle openings l4. The fact that the apertures i7 are disposed in a relatively thin plate adapts them under Well known physical laws to have a variable co-etiicient of discharge thereby providing a factor regulative of the degree of suction which will exist within the mixing chamber portion of the carbu7 retor in `proportion toany given de ree of throttle opening. .If it were not aor the variable co-eiiicient' v of discharge of the openings 17, it will be obvious that with an unchanged throttle setting, the How of air would vary in accordance with variations in the air head` which induces' flow; but the variation in How would not be exactly proportional to the variation in head.

s the air head is increased, whether by the increased speed of the engine or otherwise, the ow of air will be correspondingly increased, but, due to the resistance offered to the passage of the air by the ports through which it is obliged to pass in traversing the carburetor, the increased flow can occur. only at the expense of air density so that ifthe co-ecient of discharge of each port'remains constant the density of the air will gradually decrease; Thus, the liow of air as measured by yweight Will not be exactly proportional to the change of air head which induces that How.

r.lhe above facts, with regard to the flow of air, do nothold with regard to the flow o' liquid. rlhe vincrease in head, such as might be caused by increased suction at the outlet end of the carburetor, will cause a. variationl in liquid low which will tend to be exactly proportional to the variation in head Thus, if one relatively low air head' be taken as unity and the fuel supply passage 'is so proportioned to the air inlet ports 17 that at this unithead there will be fteen units of air i'low through port 17 in proportion to one unit of fuel weight,

then, as the air head is increased to tive units of'head the fuel How will tend to increase in exactly the same proportion to produce a ow ot ive units oi fuel. But, due to the-lawatoresaid, the air dow will not maintain the proportion, but, in the absence or a properly designed port at `17 will fall below the 75 units of air.

ln order to overcome this tendency the i ports 17 are so constructed as to take advantage ot the law relating to the iow of gases through orifices in thin plates. rlhus, the resistance oered byportsl-Z to air dow through said ports decreases as the rate ot allow increases, the air liows through said ports without change in density, and thus the air-fuel mixture is maintained substantiaily constant.

l'. have found, however, that at high air speeds the co-ecient oi? discharge ot orices '17 does not become suliciently vincreased to counter-act a, tendency for the air to become rarer at such speeds." Accordingly, l designed the constricting wall 5, and by experiment have found that it .exerts a modifying eiiect upon the variation of co-ecient of discharge of ports 17 whereby at lrelatively high air speeds the co-eiiicient of discharge of said ports will be relatively greater with respect to their `co-efiicient of discharge at low air speeds than would be the case in the absence of the constricting Wall 5". lt should be noted, however, that thewall 5 does not consti-ict air flow in the ordinary sense of the term slnce the area of the opening bounded by said wallis suiicientlargc to permit the unimpeded flow of the maximum quantity of air which can, under like circumstances, pass through the ports 17.

rlhe operation ot' the fuel pump 'in regulating fuel flow under abnormal conditions for the purpose of maintaining the mixture substantially constant has already been described and will not be repeated atl this point.

It will be seen from the foregoing that l have designed a carburetor which is adapted to maintain a substantially constant mixture under all working conditions. By way of summary, it'may be'noted at this point that for fixed throttle positions the carburetor automatically. compensates for changes in air head solely through the variable co-'eflicients of discharge of ports 17 as modified by the presence of wall 5, all other factors within the carburetor being so designed as to be constant or substantially so; and that for those abnormal conditions which are created at the time when the throttle valve member isV adjusted simultaneously to open or close ports 14 and 17, compensation is made by the pump, which maintains the mixture constant until the air How becomes stabilized and reaches the rate corresponding to the areas of the particular openings afforded by the valve in its new setting.

Although the relative sizes of the various ports, passages, and openings in this carburetor are disclosed in their proper proportions in the accompanying drawing, l will nevertheless state herein what such sizes are in order that those skilleddn the art may duplicate this carburetor with the least possible degree of diiiiculty. 'llhe diameter of the Venturi passage through plug 42 at its throat is .O39 inch. rlhe area of passage 43 at its upperend is .0818 square inch. The length of the passage 43 is 3 l open throttle is As shown, there are six of such ports, and the altitude of each triangular opening from the base to the apex thereof at wide 5/8 of an inch. The combined area of ports 17 is 1.4498 square inches at wide open throttle. There are eight of such ports, and the altitude of each from the base to the apex thereof is .57206 inch. The base line of each is .6312 inch. The area of the annular space between the throttle valve andthe wall portion 5 is 1.36355 square inches. l have found by experiment that a carburetor constructed in accordance with the disclosure in the drawings of this'- used successfully upon.

application can be different types of engines, within its capacity, without modification. 1` ascribe this fact to-my Carburetor design whereby the mixture of fuel and air is maintained constant so that a given quantity of air'passing through my carburetor is always carbureted substantially to the same degree. Thus, irrespective of the engine requirements, within the capacity of the carburetor, an ideally perfect mixture or substantially such is supplied at all times, regardless of the quantity of mixture flow in a given space of time. l

Furthermore, have discovered by actual tests that an engine equipped with a carburetor constructed in accordance with the disclosure in the accompanying drawingl will remain much cooler than when the same engine is equipped withany other' make of carburetor with which I am familiar.

I claim:

1. A carburetor having means defining inlet and outlet ports of adjustable area, said means being adjustable to vary simultaneously the areas of said ports in proportions adapted to maintain the degree of vacuum between said ports in any given setting of said means', a fuel inlet leading to said carburetor with its discharge end exposed to said vacuum and having a normally substantially constant co-eflicient of efflux, and a source of fuel supply under substantially constant head and arranged for fuel delivery through said inlet, whereby fuel flow will be roportioned to the degreeof vacuum a oresaid and'to the rate of air flow.

2. A carburetor having means defining inlet and outlet ports of adjustable area, said means being adjustable to vary simultaneously the areas of said ports in proportions adapted to maintain the degree of vacnum between said ports proportionate to air flow in any given setting of said means, a fuel inlet leadin to Said carburetor with its discharge en exposed to said vacuum and havinfr a normally substantially constant co-efcient of efflux, and a source of' fuel supply under substantially constant head and arranged for fu el delivery through proportionate to air flow.

said inlet, whereby fuel flow will be proportioned tothe degree of vacuum aforesaid and to the rate of air ow, said inlet port having a co-eiicient of eilux variable with the rate of How at any given setting of said means, whereby the density of air entering said port will be maintained substantially constant.

3. A carburetor comprising a main casing having air inlet and mixture outlet passages, a throttle Valve in the form of a sleeve, controlling spaced triangular ports at the air inletand mixture outlet passages, Said throttle valve adapted to vary the opening of the ports in different amounts for each setting of said throttle valve, a source of fuel supply, and a Venturi fuel nozzle of substantially constant co-eiicient of discharge having a submerged entrance and communicating with the space between the ports. 4. A carburetor comprising a casing havlng air inlet and mixture outlet passages; a throttle valve provided with air and mixture controlling portions, said portions and the casing adjacent thereto being formed and adapted, during the opening movement of said valve, to enlarge progressively the air passage with vdecreasing increments of change and to enlarge progressively the mixture passagel with increasing increments of change; a source of fuel su ply; a Venturi nozzle adapted to receive uel under ressure from said source; and a passage eading from said nozzle to the interior of said carburetor between Said air and mixture passages, said last mentioned passage having its cross sectional area expanded at a constant rate in the direction of fuel flow therethrough to a diameter having a maximum fuel vapor capacity proportioned to the maximum capacity of said air inlet passage substantially in the proportions of mixture desired.

5. A carburetor comprising a casing havin an intake passage therein, a throttle va ve, means co-operating with the throttle valve to form a mixture outlet port having a substantially constant co-eicient of discharge and an air inlet port with a co-eicient of discharge variable in proportion to air speeds; fuel supply means havin a. substantially constant co-eicient of' charge leading to said carburetor.

6. A carburetor comprising a casing, a valve member therein, said casing and said valve member being formed to provide air inlet and mixture-outlet orts variable by the operation of said mem r with inversely varying increments of change, a Venturi fuel supply pass e communicating with said carburetor'an having a substantially constant co-eiicient of elux, fuel suppl means lea to said passage with norma ly substantie ly constant hydrostatic held,

ports variable by the movement of said' valve member with inversely varying increments of change, said mixture outlet port being formed to have a substantially constant co-eficient of eilux and said air inlet port being formed to have a co-efcient of elux varying in proportion to air flow therethrough, a chamber, means for maintaining fuel at a substantially constant level therein, a Venturi jet at a level below the level f fuel in said chamber and in com- `munication with the interior of said chamber, a passage between said jet and the inteior of said carburetor formed to provide cross sectional areas expanding at a constant rate in the direction of fuel iiow, and means operatively connected with said throttle for varying the effective hydrostatic head of fuel lat said Venturi nozzle, whereby said fuel is accelerated positively during the opening movement of said throttle a'nd negatively during the closing movement of said throttle.

8. In a carburetor having an air inlet port with a co-eilicient of discharge variable in proportion to air flow` and a mixture port having a substantially constant co-elicient of discharge, means "for simultaneously varying the areas of said ports at a variable rate with inversely varying increments of change, and fuel supply means including a passage provided with a Venturi throat in communication with the interior of said carburetor.

9. A carburetor including a casing provided with inlet and outlet passages, a Venturi metering nozzle provided with a flaring discharge passage in communication with the interior of said carburetor, a source of fuel supply normally maintained at a level above the'throat of'said nozzle, a plurality of pyramidal projections spaced concentrically about the discharge end of said fuel passage and providing triangular ports communicating with the discharge passage of said carburetor casing, afsleeve valve movable within said casing and provided with triangular ports, said sleeve valve being adapted to close and open the rst mentioned ports and said casing being adapted, upon the movement of said valve, to close and open the ports therein, said last mentioned ports having a variable co-efficient of discharge.

10. A carburetor comprising a casing having air inlet and outlet passages communicating therethrough, a throttle valve within said casing having two component parts respectively controlling said inlet and outlet passages, and a Venturi fuel nozzle communicating with the space between the component parts of the throttle valve, said parts being arranged to control the areas of the inlet and outlet passages with varying rates of change, suchfareas as are controlled b the valve and the area of the fuel passage eing so formed proportioned that in the various positions of the valve at any given setting thereof ,the capacity of the fuel passage will `be proportioned to the capacity of the inlet passage in substantially the desired ratio-toair and the combined capacity of the inlet passage and fuel passage will be substantially equal to the capacity of said discharge passage.`

11. In a carburetor having passages therethrough, the combination of a compound throttle valve adapted to simultaneously constrict the passages atv separated points and defining ports at said points, one of which has asubstantially constant co-eflicient lof eliux and the other of which has a variable co-eihcient of` efflux, a fuel nozzle communicating with the space between the said points, whereby .fuel is drawn into said space by the partial vacuum produced therein, the relative constriction at the separated points being such that the supply of fuel varies substantially in accordance with the quantity of air passing through said carburetor, and means to temporarily compensate for a sudden change in the setting of the throttle valve.

12. In a carburetor, the combination with a casing having a passage therethrough providing inlet and outlet ports, of a throttle valve co-operating with said ports, and al fuel supply duct communicating with said passage intermediate said ports, said inlet port having a variable co-eiticient of discharge approaching maximum efficiency as the flow of air therethrough approaches a maximum, and the co-efficient of discharge of said outlet port being substantially fixed at a proximately the maximum efficiency of discharge'toward which said inlet port approaches.

13.. A carburetor including the combination with a casing having a passage therethrough, of a series of projections formedI second port in substantially the proportion of fuel to air desired in the eiiiux from said carburetor, and the forms of said first and second ports being determined to control the degree ofIsub-atmosphericpressure at the Venturi passage and so calculated for different positions of the throttle valve that at any given setting, the capacity of said first port will exceed the capacity of the second port by the amount of fuel vapor required to maintain the desired ratio of fuel to air as aforesaid.

14. A carburetor including a casing having a passage therethrough, means providing a mixture port having a substantially constant co-etticient of discharge, means providing an air ort having a co-eicient of discharge variab e in proportion to air flow, means for simultaneously adjusting the areas of said ports with varying increments of change, a Venturi fuel passage discharging into said casing passage in the path of air moving between said ports, a fuel chamber in communication with said Venturi passage and adapted to maintain fuel at a level above the throat of said Venturi passage, a jet aligned with said venturi and communicatin therewith, and a pump connected with said adjusting means and communicating with said jet.

15. A carburetor having a passage therethrough with inlet and outlet ports of variable area at spaced. points in said passage and formed to have variable and substantially constant co-etiicients of discharge respectively, and a fuel inlet passage communieating with said first mentioned passage between said ports and having a Venturi throat formed therein and a substantially constant co-eihcient of discharge, and means for varying the areas of said inlet and outlet ports in predetermined proportions which are adapted to produce a degree of vacuum adjacent said fuel passage proportioned to the air flow in any given setting of said means. A l

16. In a carburetor, the combination of a main throttle valve adapted to constrict the-flow of air through the carburetor at two spaced points, fuel supply means entering the space between such points and controlled by the partial vacuum created in such space, said carburetor having orifices, adjacent the inlet portion, which have a co-eicient of discharge increasing with increasing velocity, said fuel supply means having an orifice through which the fuel passes, which has a substantially constant co-efiicient of discharge, whereby a substantially constant mixture is maintained.

In testimony whereof I atiix my signature.

WILLIAM SCI-IOOF. 

